PROJECT SUMMARY More than a dozen municipalities have passed healthy restaurant kids? meals policies. These policies seek to reduce child consumption of sugar-sweetened beverages (SSBs) by requiring that restaurants serve only healthy beverages (water, milk, or 100% juice) instead of SSBs as the default choice with children?s meals in restaurants. These policies have potential to meaningfully reduce child SSB consumption; 10% of child calories from SSBs come from restaurant sources. Restaurants that have voluntarily removed SSBs from children?s menus (but still allow SSBs by request) have found significant reductions in SSBs and total calories in children?s meal orders. However, there are significant gaps in our knowledge of the effects of healthy kids? meals policies on children?s health; to date, these policies have not been evaluated for their short-term effects on children?s meal orders or total dietary intake, or for their long-term effects on childhood obesity. This study makes a significant contribution by combining a natural experiment with restaurant manager and City official interviews and cost-effectiveness modeling to evaluate the implementation and health effects of a healthy restaurant kids? meals policy in Washington DC, the largest City to implement this policy to date. Our study uses a mixed-methods approach incorporating quasi-experimental difference-in-differences analyses; qualitative interviews with restaurant managers and City officials; and cost-effectiveness modeling. We will collect receipts from and survey 2,000 adults and children aged 2-10 years dining at fast-food restaurants in one intervention City with a healthy kids? meals policy (Washington DC) and one comparison City without a policy (Philadelphia, PA) to assess changes in SSBs and calories purchased before and 12 months following implementation of a healthy kids? meals policy (Aim 1). We will also conduct next-day telephone dietary recalls to assess changes in children?s SSB consumption, diet quality, and total caloric intake on the day of the restaurant meal (Aim 2). We will conduct implementation surveys in restaurants, collect local food safety inspection data from the DC Department of Public Health, and conduct interviews with restaurant managers and City officials to estimate costs, compliance, and reach of the policy in Washington DC and to model the 10- year health impact, population reach, implementation cost, healthcare cost savings, and cost-effectiveness if the policy were implemented nationwide (Aim 3). A healthy kids? meals bill was introduced in Washington DC in September 2018 and is expected to be reintroduced this month (March 2019). Advocates are confident that the bill will pass this legislative session, and implementation deadlines are typically 90 days from passage. Thus, time-sensitive funding is critical for ensuring adequate time for baseline data collection. The proposal?s significance lies in our ability to provide the first empirical evidence on the degree to which healthy kids? meals policies influence child dietary intake. Study results will provide needed evidence to inform state and local policymakers? decisions about child obesity prevention measures.